Using the WormCam (a camera sent through a wormhole in space-time), it is
possible to witness any event that is taking or has taken place in the
universe. This makes privacy essentially an obsolete concept, but also
allows us to answer many of the nagging mysteries: who painted the Mona
Lisa? Was there really a "Jesus"? Who killed JFK?

There really is not much math in the book, but I'll include it on this list
of mathematical fiction on account of the following two little tidbits:
There is a brief discussion of the metric on Minkowski space when the
inventors of the WormCam first realize that the can use it to look back in
time. A high school student uses the WormCam to look back at Pierre Fermat
as he wrote the famous marginal note that inspired so much interest in the
question of whether xn+yn=zn has any
solutions in the positive integers for n>3. Thus, he is able to determine
whether Fermat actually knew a proof, had a mistaken proof, or was merely
joking when he wrote that he knew a proof of the so-called "Fermat's Last
Theorem".